Cross-resistance and inheritance of resistance in laboratory-selected strains of the brown planthopper to various types of the insecticides were investigated. The fenobucarb-selected (), carbofuran-selected(), and diazinon-selected() strains were 50.3, 49.2 and 5.8 times less sensitive to the corresponding insecticides than th susceptible strain. both and strains were highly resistant to the other carbamate insecticides, and moderately resistant to cypermethrin and deltamethrin, but nearly not resistant to fenvalerate and the organophosphorus insecticides except malathion and phenthate. Moderate resistance to malathion and phenthoate in the and strains was obtained at the rate of 13.0-12.0 and 8.5-7.5 times, respectively. The strain showed low levels of resistance to the carbamate, organophosphorus and pyrethroid insecticides, but negatively correlated cross-resistance to fenvalerate. Resistance of the brown planthopper to all the test insecticides was inherited by partially dominant autosomal factor(s).

Cuticular penetration and detoxication as mechanisms of resistance to the carbamate insecticides in fenobucarb-selected() and carbofuran-selected() strains of the brown planthopper (N. lugens Stal) were investigated. Rates of penetration were not significantly different in the susceptible and resistant strains. However, total amount of excretion of the and strains were much larger than that of the susceptible strain. Fenovucarb and carbofuran were in vivo metabolizd much faster in the strain than in the susceptible strain. OSBP(o-sec-butyl phenol) and 3-ketocarbofuran phenol were invitro the major metabolites of fenobucarb and carbofuran in the brown planthopper, respectively. Total amount of the two major metabolites were produced abotu 2 times larger in the and strains compared to the susceptible strain. OSBP and 3-ketocarbofuran phenol were not so toxic to the brown planthopper ( >100 /g hopper). Based on our data, detoxication plays a large role in resistance to fenobucarb and carbofuran in the resistant strain of BPH, although several resistance factors maybe involved.

The optimal pH of the extraction buffer was 7.5 considiering AChE stability and its buffer capacity when AChE was isolated and extracted from the housefly(Musca domesitca L.)and three other insect species with 0.01 M sodium phosphate buffer. Also, the optimal pH of the reaction buffer was 7.5 considering enzyme activity and its buffer capacity when AChE activity was measured with the substrate in 0.1 M sodium phosphate buffer. The Potter Elvehjem type homogenizer with Teflon pestle was used to homgenize the tissues. When preparing a AChE suspension by centrifuging the homogenate, 700 g supernatant of adult head for the housefly, 700 g supernatnat of 5th instar nymphal whole body for the brown planthopper, lipid-eliminated 10,000 g supernatant of 5th instar larval whole body for the diamondback moth, and 700 g supernatant of 4th instar larval head for the tobacco cutworm were considered satisfactory as enzyme sources in view of mass preparation, extraction efficiency and stability of enzyme activity during evaluation. When AChE suspensions of 4 insect species were stored at , more than 90% of activity was maintained up to 3 weeks. Km values of AChEs of the housefly, the brown planthopper, and the diamondback moth were 0.042, 0.037 and 0.043 mM, respectively and AChE-specific substrate inhibition was observed at high concentration. Km value of the tobacco cutworm ChE was 1.15 mM and BuChE characteristics was observed, though further study is needed. The optimal substrate concentration for the AChE inhibition tests was 0.5 mM for the housfly, the brown planthopper, and the diamondback moth and 12 mM for the tobacco cutworm.

Studies were carried out to investigate structural characteristics of the larval and adult light organs of Luciola lateralis Mot. and to observe the relation between the light organ and nerve. The larval light organs, (LLO)existed at a paired dorsal lateral positions of the 8th abdominal segment. The organ was spherical or sub-spherical in shape. There were many vacuoles around the LLO. As larva grew, the number of vacuoles increased. LLO had the muscles in its interior part and their role seemed to fix the LLO position in space. Also, there were the tracheae and tracheoles in LLO. The Adult light organs (ALO) were at the ventral portions of the 5th and 6th abdominal segments in the male, but only on the 5th abdominal segment in the female. ALO had two functional layers, i.e., photocyte and dorsal layer. Tracheal end organs existed in both layers but their arrangements were irregular. Rod-shaped photocytes and spherical photocytes were observed in the ALO of male and female, but the rod-shaped types were rarely found in the female. In the ALO of the 5th abdominal segment, two paired peripheral nerves were originated from the anterior part of the last abdominal compound ganglion. A pair of peripheral nerves were originated from the posterior part of the compound ganglion to innervate the 6th abdominal segment ALO. And LLO was innervated by a paired peripheral nerves from the last abdominal ganglion.

Laboratory experiments were conducted to examine the effects of soil moisture on the survival of the larger black chafer(Holotrichia morosa Waterhouse) eggs and larvae. Survival rates of eggs and 1st, 2nd, and 3rd instar larvae were all above 79% at soil moisture of 15% and 25% in sandy loam and clay loam soil, but decreased considerably at 5% and 35%. At these extreme moistures there seem to be differences in survival rates of eggs and larvae between soil textures. Egg development was delayed as soil moisture approached to the lower limit for survival. Older eggs were tolerant to the high moisture stress(33-36 % , clay loam soil), and duration of the stress affected egg development. Feeding of 3rd instar larvae was obviously suppressed at the higher level of soil moisture.

The entomopathogenic nematodes, Steinernema carpocapsae and Heterorhabditis bacteriophoTa, were laboratory tested for the control of rice stem borer Chilo suppressalis. When 8 cm long of two rice stems infected by rice stem borers were treated with S. carpocapsae by spray application to the concentrations of 250, 500, 1,000, or 2,000 nematodes/ml, 68.6 10.0-94.9 2.6 % control was obtained. When 8 cm long of rice stems infected by rice stem borers were treated with H. bacteriophoTa by spray application to the concentrations of 100, 200, 400, or 800 nematodes/ ml, 91.4 0.7-100 % control was obtained. On the other hand, when 8 cm long of three rice stems were treated with H. bacteriophora by dipping application to the concentrations of 100 or 200 nematodes/ml, 46.2 4.7-63.1 4.7 % control was obtained. Because the moist habitat of rice stems were favorable to nematode survival and searching abilities, entomopathogenic nematode, were confirmed to be a potential biological control agents against rice stem borers.

This study was carried out to investigate the occurrence of bug species around bank and paddy field and its peckey rice in four different districts of Kyonggi Area, and then to observe the distribution of bug species causing pee key rice. The results obtained were as follows; Thirty one bug species were collected around bank and its dominant species were Eyarcoris parvus, Nabis stenoferus, Stictopleurus crassicornis and each constituted 35.9, 20.2, 6.5 %, respectively. On the other hand, 11 bug species in paddy field were identified and the dominant species among them were Nabis stenoferus, Adelphocoris triannulatus, Eyarcoris parvus. Pee key rice induced by the infestation of bug species was 34.7% in Eyarcoris parvus and 2.7% in Aeschynteles maculatus. The occurrence of pecked rice injured by bugs was severe on milk ripe stage through heading stage to yellow ripe stage of rice growth period. Peckey rice among rice varieties was higher in Sobaekbyeo, extremely early mature variety, and Taebaegbyeo, early mature variety. The occurrence of peckey rice was higher in mountainous area such as Pocheon culturing early mature rice varieties.

In order to investigate the species composition and the colony density of ants in Mt. Namsan, Seoul, 39 quadrats were installed in 13 vegetations, 443 colonies of ants were collected from June, 1989 to October, 1990. As the result, 4 subfamilies, 23 genera, 28 species was confirmed. Among them, Cerapachys humicola is new to Korean fauna along with the subfamily Cerapachinae. For the species composition of ant communities in each vegetation, Robinia pseudoacacia vegetation(containing 3 subfamilies, 14 genera, 15 species-53.6% of all colonies collected in Mt. Namsan) and Quercus mongolica vegetation (3 subfamiles, 12 genera, 14 species -50%) showed relatively rich composition, while Platunus orientalis vegetation (3 subfamilies, 3 genera, 3 species) showed the simplest composition. Colony density was the highest in Prunus sargentii vegetation (7.875 colony /) and the lowest in Platunus orientalis (1.000 colony/). The relative density of Paratrechina flavipes proved to be the highest (RD = 0.422) and that of Cerapachys humicola Massor aciculatus was the lowest (RD = O. 002 respectively). In the analysis of the similarity of ant communities between each vegetation by S¢rensen's coefficient, Prunus sargentii was very similar to Sorbus alnifolia (0.745) and Pinus densiflora (0.736), but had the lowest similarity to Metasequoia glyptostoboides and Chamaecyparis pisifera vegetation (0.164 respectively). Dominance of ants in each vegetation analyzed by Simpson'formula was found to be high in Platunus orientalis ( = 0.393) and Sorbus alnifolia ( = 0.392) and the lowest in Metasequoia glyptostroboides vegetation(= 0.067). The analysis of diversity by reverse Simpson's coefficient revealed that it was high in Metasequoia glyptostroboides ( = 14.925), Pinus rigida ( = 7.874) and was the lowest in Platunus orientalis vegetation ( = 2.545). Evenness calculated by using d. and (maximal diversity) was high in Metasequoia glyptostroboides ( = 0.714) and Chamaecyparis pisifera vegetation ( = 0.624). On the contrary, Quercus mongo/ica vegetation had the lowest value of evenness ( = 0.182).

For the study of ant fauna in Mt. Kyeryongsan, we selected three areas and collected 317 colonies nine times from 1986 to 1990. The communities of ants were composed of 3 subfamilies, 23 genera and 45 species. Among them, Solenopsis sp. was an unrecorded species in Korea. The number of ant species distributed in each area was almost the same, and the species distributed uniformly in the nine subareas were Paratrechina flavipes and Aphaenogaster japonica. The number of species collected in the only one subarea were ten, and six among them were collected in the area of Sinwonsa temple, the westward slope. It is remarkable that Camponotus tokioensis, which is known to be distributed only in the island and coast so far, is found to be distributed in the area of Sinwonsa temple as well.

Adult eclosion and emergence behavior of the black pine base scale, Matsucoccus thunbergianae Miller and Park, was studied in a laboratory. Adult eclosion in males did not appear to be limited to a specific time of the day. Newly molted male adults, at room temperatures, usually remained in the cocoons as pre-emergence adults for 0.5-20. days before emerging; most males emerged within one hour after the onset of photophase, and emergence was faster at higher light intensity. Most females molted into adults within three hours after the onset of photophase, and they were active immediately after molting. Quiescence in males appears to help the scales concentrate their sexual activity within a particular period of the day as well as to protect newly molted adults until sexual and locomotive maturity.

The daily rhythm of sex pheromone production and release by females of the black pine base scale, Matsucoccus thunbergianae Miller and Park, was demonstrated by studying the amounts of pheromone possessed and released by females, periodically after emergence. Cycles of both pheromone production and release had daily peaks between 8 a.m. and 2 p.m., and has marked decreases after 4 p.m. It appeared that the amounts of pheromone gradually decreased three days after the emergence. Significance in synchronization of the daily rhythm of female pheromone release and activities of males and females with reference to reproductive success in this species is discussed.